Skip to contentVPN and proxy glossary
Clear, honest definitions of the VPN and proxy terms you will meet across s4m and the wider industry. Bookmark this page as a quick reference while you set up a tunnel or route traffic through a proxy.
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Every term with its own in-depth page — browse the full list page by page.
Perfect Forward Secrecy
Perfect forward secrecy ensures a stolen long-term key cannot decrypt past traffic. Learn how ephemeral keys protect sessions in VPNs and TLS.
Read →Ping
Ping is a tool and a measurement of round-trip time to a host using ICMP echo. Learn how to read ping results and what a proxy hop adds to them.
Read →Port Forwarding
Port forwarding directs incoming connections on a specific port to a device behind a router or NAT. Learn how it works and its relation to CGNAT.
Read →Proxy Authentication
Proxy authentication is how a proxy verifies who may use it, by credentials or IP. Learn the HTTP and SOCKS5 methods s4m uses to secure its proxies.
Read →Proxy Chain
A proxy chain routes traffic through several proxies in sequence for layered anonymity. Learn how chaining works and its speed trade-offs.
Read →Proxy Pool
A proxy pool is a collection of IPs you rotate through to distribute requests. Learn how pools power rotation and how to manage one well.
Read →Proxy Scraping
Proxy scraping is harvesting public proxy servers from open sources. Learn why most free proxies are unreliable and how s4m validates its list.
Read →Proxy Server
A proxy server relays requests between clients and destinations, masking the origin IP. Learn the main types and how s4m runs its proxy servers.
Read →QUIC
QUIC is a fast transport protocol built on UDP that underpins HTTP/3. Learn how it cuts connection setup time and why proxies handle it differently.
Read →RAM-Only Server
RAM-only describes volatile local storage, not a guarantee that no data is retained elsewhere. Learn its scope and limits.
Read →REALITY
REALITY is a camouflage layer for VLESS that borrows a real website's TLS identity to defeat censorship. Learn how it works and how it relates to s4m.
Read →Rate Limiting
Rate limiting caps how many requests a client may make in a window to protect a service. Learn how it triggers blocks and how to work within limits.
Read →Residential Proxy
A residential proxy routes traffic through a real home ISP IP, blending in with ordinary users. Learn its trade-offs versus the datacenter proxies s4m offers.
Read →Reverse Proxy
A reverse proxy sits in front of servers, handling incoming requests, TLS and load balancing. Learn how it differs from the forward proxies s4m sells.
Read →Rotating Proxy
A rotating proxy changes your exit IP automatically across a pool, spreading requests to avoid per-IP limits. Learn when to rotate versus stay static.
Read →SOCKS4
SOCKS4 is an early proxy protocol that relays TCP without authentication or UDP. Learn how it differs from SOCKS5 and why SOCKS5 replaced it.
Read →SOCKS5
SOCKS5 is a versatile proxy protocol that relays TCP and UDP traffic for any application. Learn how it works and how s4m runs SOCKS5 on port 1080.
Read →SOCKS5 Authentication
SOCKS5 authentication controls who may use a SOCKS5 proxy, usually via username and password. Learn how s4m secures its SOCKS5 proxy on port 1080.
Read →Session Persistence
Session persistence keeps a series of requests recognised as one continuous session. Learn how IPs, cookies and sticky sessions maintain continuity.
Read →Shadowsocks
Shadowsocks is an encrypted proxy built to bypass censorship by disguising traffic. Learn how it works and how it differs from the VPN s4m offers.
Read →Shared Proxy
A shared proxy is used by several people at once, which is cheap but risks inherited blocks. Learn how it compares to a dedicated IP.
Read →Sneaker Proxy
A sneaker proxy is a proxy used for limited-release retail drops. Learn what these buyers look for and how s4m's datacenter proxy offering relates.
Read →Split Tunneling
Split tunneling lets you send some apps through the VPN while others use your normal connection. Learn its uses and its privacy trade-offs.
Read →Static Proxy
A static proxy keeps you on one fixed exit IP, ideal for logins, whitelisting and stable sessions. Learn how it compares to a rotating proxy.
Read →Ready to hide your IP?
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